1. Field of the Invention
The present invention relates to a toner reservoir, a process cartridge, and a developing apparatus.
2. Description of the Related Art
Conventionally, a toner-supplying belt is received in a groove formed in a side frame. The toner-supplying belt is driven to run along the groove, thereby transporting toner.
FIG. 20 is a side view of a conventional process cartridge.
Referring to FIG. 20, a print process cartridge 34 includes a photoconductive drum 19, a charging unit, not shown, a developing unit 65, and a recycling unit. The photoconductive drum 19 is driven in rotation by a drum motor, not shown, and bears a toner image thereon. The charging unit is disposed to oppose and charge the surface of photoconductive drum 19 uniformly before an electrostatic latent image is formed on the surface. The developing unit 65 deposits toner, not shown, to an electrostatic latent image formed on the surface of the photoconductive drum 19, thereby developing an electrostatic latent image on the into a toner image. The recycling unit removes residual toner from the surface of the photoconductive drum 19 after transferring and sends the residual toner back to the developing unit 65. The developing unit 65 includes, for example, a developing roller 21 and a toner-supplying roller 67. The developing roller 21 is disposed to oppose the photoconductive drum 19 while the toner-supplying roller 67 supplies the toner to the developing roller 21.
A developing apparatus is constructed of the developing unit 65 and recycling unit, and functions as a toner reservoir.
The recycling unit includes a cleaning section 66, a toner-collecting chamber 71, and a groove 35 that is formed in a side frame to describe a loop. The cleaning section 66 includes a blade 37a, a residual toner chamber 66a, and a screw conveyor 38 for collecting toner. The blade scrapes the residual toner of the surface of the photoconductive drum 19. The residual toner chamber 66a extends along an axis of the photoconductive drum 19 and holds the residual toner therein. The screw conveyor 38 transports the residual toner collected in the toner chamber 66a to the print process cartridge 34.
The groove 35 runs beside, for example, the shafts of the photoconductive drum 19, developing roller 21, and toner supplying roller 67, which cooperate in a printing operation performed in the print process cartridge 34. The groove 35 receives an endless toner-transporting belt 36 having a loop length slightly longer than an inner loop length of the groove 35. A motor, not shown, drives a drive gear 39 to rotate in a direction shown by arrow A. The drive gear 39 in turn drives a driven gear 82 to rotate in a direction shown by arrow B. As a result, the toner-transporting belt 36 is driven to run in the groove 35 in a direction shown by arrow C. The side frame 10 has a substantially U-shaped space that is formed at an upper portion thereof and accommodates a pulley 79 therein. The pulley 79 receives the toner-transporting belt 36 to facilitate smooth running of the toner transporting belt 36.
The groove 35 communicates with one end of the residual toner chamber 66a at a toner receiving port P1. The toner transporting belt 36 is partially exposed in the residual toner chamber 66a, so that the toner-transporting belt 36 receives the residual toner held in the residual toner chamber 66a and transports the residual toner in the C direction. The toner-transporting belt 36 has a plurality of projections 36a. A toner receiving recess is defined between adjacent projections 36a. 
The groove 35 communicates with the toner-collecting chamber 71 at a toner discharging port P2 where the toner-transporting belt 36 is exposed in the toner-collecting chamber 71 to allow the residual toner to fall into the toner-collecting chamber 71. A screw conveyor 40 extends through the toner-collecting chamber 71 and delivers the residual toner back to a toner cartridge.
A gear 73 is attached to the screw conveyor 40 and is in mesh with the toner-transporting belt 36. As the toner-transporting belt 36 runs, the gear 73 is rotated so that the screw conveyor 40 rotates. The screw conveyor 40 has spiral vanes formed thereon, the vanes transporting the residual toner from the side frame 10 to a waste toner chamber in the toner cartridge (reference is made to Japanese Patent Laid-Open No. 2001-18224).
The driven gear 72 is in mesh with the projections 36a formed on the toner-transporting belt 36, so that the rotational force of the driven gear 72 causes the toner-transporting belt 36 to run to transport the residual toner.
The structure for rotatably supporting the gear 72 will be described.
FIG. 21 is a side view of a shaft-supporting structure for a conventional belt-driving gear.
FIG. 22 is a perspective view.
FIG. 23 is an exploded view.
FIG. 24 is a front view.
FIG. 25 is a cross-sectional view taken along line A—A of FIG. 24.
Referring to the figures, a shaft 75 is mounted on the side frame 10 and supports the gear 72 in such a way that gear 72 rotates frictionally slidably on the shaft 75. The gear 72 is in the shape of a large-diameter gear section with gear teeth formed in its circumferential surface and has small-diameter bosses 77 and 78 that project in opposite directions from the gear section. The shaft 75 includes a large-diameter portion 75a and a small-diameter portion 75b. The large-diameter portion 75a has a circular cross-section and is mounted on the side frame 10 while the small-diameter portion 75b fits into the hole 80.
There is a gap between the outer surface of the small-diameter portion 75b and the inner circumferential surface of the gear 72. The gear 72 rotates frictionally slidably rotate on the shaft 75.
A cover, not shown, is attached to the side frame 10 to prevent the residual toner in the groove 35 (FIG. 20) from leaking. Upon mounting the cover to the side frame 10, the cover abuts the end of the boss 77 to prevent the gear 72 pulling out from the shaft 75.
However, with the aforementioned conventional print process cartridge, as the toner-transporting belt 36 runs, the residual toner held in the recess between adjacent projections 36a is supplied to the gear 72, entering gaps between the shaft 75 and the gear 72. As a result, the gear 72 cannot be rotated smoothly.